Patch Tuesday surprise: Microsoft unexpectedly issues patches for 24 critical Internet Explorer flaws

Microsoft has issued patches for 24 vulnerabilities in Internet Explorer, fixes that the company didn't disclose in its preliminary listing of security bulletins it released last week.

The most severe of these could allow attackers to execute malicious code remotely by enticing users to view specially crafted Web pages. Successful exploits against the most severe flaws could gain the same rights as the user who is logged in, so if someone were logged in as an administrator, the attacker would gain administrative rights, according to a blog on the Microsoft Security Response Center page.

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This cumulative IE update Microsoft hasn't patched IE in two months should be given the highest deployment priority among this month's fixes, says Russ Ernst, director of product management for Lumension.

While none of the vulnerabilities is known to have been exploited, Microsoft rates 12 of them as "exploit code likely." Only one of the vulnerabilities had been publicly disclosed before this. The others were reported to Microsoft privately, the company's security bulletin summary says.

They all affect IE versions from 6 through 10, which impacts Windows XP, Vista, Windows 7 and Windows 8.1.

It surprised some experts that IE bulletins were lacking in last week's preview of security bulletins. "It's possible Microsoft wanted to give some last minute quality attention to the bulletin prior to release," says Ernst.

A second critical bulletin to pop up since last week's preview addresses flaws that leave VBScripting vulnerable to remote code execution if users are lured to a specially designed Web site, Microsoft says.

That brings the number of this month's bulletins to seven, four of them critical.

One addresses problems with DirectWrite that could allow remote code execution, and attacks exploiting them are expected within 30 days, Microsoft says.

The other critical bulletin is for Microsoft Forefront Protection for Exchange Server 2010, which is security technology for the email server. Microsoft stopped updating Forefront in September 2012, but continues to support it with security updates. Ernst says this should prompt users to upgrade. "This is an example of Microsoft honoring their commitment to fixing any security gaps in this application, but this should make administrators think about upgrading their Exchange servers to the latest version (which includes basic anti-malware protection by default) or consider a third party email security application," he says. "Administrators that currently use Forefront Protection for Exchange have until December 2015 to get this done."

Tim Greene covers Microsoft and unified communications for Network World and writes the Mostly Microsoft blog. Reach him at and follow him on Twitter@Tim_Greene.

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